Apparatus and method for testing using dynamometer

ABSTRACT

A test method includes deriving road grade information or wind load information from test schedule torque outputs generated by a dynamometer operatively arranged with a first vehicle, and controlling an accelerator pedal, an accelerator pedal signal, a fuel injector, a manifold pressure, a motor controller, or a throttle valve associated with the first or a second vehicle according to a speed schedule such that the dynamometer, or another dynamometer, programmed with the road grade information or wind load information and operatively arranged with the first or second vehicle applies a load to the first or second vehicle that reflects the road grade information or wind load information.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional App. No.62/610,541, filed Dec. 27, 2017, the contents of which are incorporatedby reference herein.

BACKGROUND

The present disclosure is in the technical field of automotive exhaustgas emissions measurement and analysis and the measurement of the energyefficiency of vehicles. More specifically, it is in the field ofpredicting the exhaust gas emissions of vehicles with InternalCombustion Engines (ICEs), including the emissions from Hybrid ElectricVehicles (HEVs) and predicting the energy efficiency of vehicles for allpowertrain types operating in the real world, based on simulatingreal-world conditions during laboratory testing.

Modern automobiles with ICEs can operate reliably under almost anycombination of environmental, road grade, and driving conditions foundon Earth. Such vehicles are common throughout the world and operateregularly and reliably in ambient temperatures ranging from well below 0C to more than 40 C, from dry desert conditions to humid rainforests,and in bumper-to-bumper, slow city traffic to high speed operation onthe German Autobahn.

Many countries that host large numbers of automobiles have exhaust gasemissions standards, i.e. “tailpipe” standards that auto manufacturersmust comply with. But experience has shown that it is difficult andexpensive to test vehicles under the broad range of real-worldenvironmental, road, and driving conditions that are known to affectemissions and fuel economy of vehicles in the real world. And it is wellknown that the energy efficiency of HEVs and the range of BEVs on asingle charge decrease at lower ambient temperatures.

Laboratory-based tailpipe emissions testing has been historicallyperformed under a limited range of ambient conditions, vehicle speedpatterns, and driving conditions. Because the number of vehicles hasincreased dramatically in recent years worldwide, and because vehicleshave become increasingly computer-controlled, it has become necessaryfor governments and automobile manufacturers to better understand theemissions of vehicles across a wider range of operating conditions sothat National Ambient Air Quality (NAAQ) standards can continue to bemet in current ambient air “attainment areas” and can eventually be metin current “non-attainment areas.” It has also become necessary forvehicle manufacturers to be able to assess the effects of changes tovehicle emission controls and powertrain calibrations across a widerrange of ambient and operating conditions.

New vehicle exhaust gas emissions regulations are driven, in part, bymeasured levels of NAAQ for specific criteria pollutants that are knownto directly or indirectly affect human health and for the control ofgreenhouse gas emissions. NAAQ levels vary widely throughout the world,depending on both mobile emissions sources and stationary sources ofpollution. Population densities, weather conditions, vehicle emissionsperformance, the age and makeup of the local in-use vehicle fleet,stationary sources of air pollution, and geographic features, are allfactors affecting NAAQ. For example, the air quality in SouthernCalifornia can be particularly poor because of a high populationdensity, combined with a well-known atmospheric temperature inversiondue to geographic features and atmospheric conditions.

Automobiles and trucks with ICEs contribute to the overall pollutionfrom “mobile sources,” most notably from “tailpipe emissions.” And BEVscontribute to “stationary sources” of pollution, i.e. emissions fromelectrical power plants. The tailpipe emissions and energy efficiency ofany particular vehicle operating in the real world is dependent on manyfactors, including various environmental conditions, road grade, driverbehavior, traffic conditions, and the effectiveness of the vehicle'semissions controls related to those factors.

BEVs may become a significant factor of overall pollution from“stationary sources” in the future if they are produced in increasinglylarger numbers because they get their energy from the power grid.Therefore, it is important to understand the energy efficiency of BEVsin real-world driving as well.

The promulgation of new emissions standards for controlling criteriapollutant and greenhouse gas emissions from vehicles with ICEs has beentraditionally linked to a laboratory-based testing regime and relatedmethodologies because laboratory-based testing can be very repeatableand because mass-based, real-world (i.e. on-road) testing had not beenpossible until recently, i.e. since the commercialization of PortableEmissions Measurement Systems (PEMS).

While laboratory testing methods are known to be very accurate andrepeatable for emissions measurements under actual test conditions,real-world driving can subject a vehicle to a wide range of conditionsthat traditional laboratory testing protocols would not. There are manyreasons for this, including the difficulty of simulating the full rangeof real-world temperature and atmospheric pressure conditions in thelaboratory, the effects of real-world driver behavior under actualtraffic conditions, etc.

To address the limitations of a laboratory-only testing regime for ICEvehicles, PEMS apparatuses and methods for conducting accurate,real-world testing of exhaust gas mass emissions and fuel economy frommoving vehicles while they are driven in the real world have beendeveloped. This has become increasingly important in understandingvehicle emissions that affect NAAQ, greenhouse gas emissions, and avehicle's fuel economy.

Over the past 20 years, PEMS has become a commercial product widely usedby both regulators and automobile manufacturers. For example,PEMS-based, real-world testing has become a required test methodologyfor the vehicle certification process in the European Union, starting in2017. But laboratory testing continues to be a valuable tool for vehiclemanufacturers during the vehicle development process and for regulatorsbecause the testing protocols produce very repeatable test results. Forexample, the effects on tailpipe emissions of large and small changes toa vehicle or powertrain can be precisely determined by repeat testsafter introducing such changes.

SUMMARY

Here, certain embodiments may relate to conducting accurate andrepeatable exhaust gas mass emissions testing of ICE vehicles and energyefficiency measurements of all vehicle types-measurements that arerepresentative of the real-world energy efficiency and tailpipeemissions, where applicable, for any vehicle model, on any route, andover any set of ambient conditions of interest. More specifically,certain embodiments relate to an apparatus and method for measuring theemissions and energy efficiency performance of a vehicle under a broadrange of real-world driving conditions by conducting testing primarilyin a laboratory. For example, a vehicle test method may includeoperating a vehicle and dynamometer, configured to provide road load tothe vehicle, respectively according to a real-world vehicle throttleschedule and a real-world speed schedule defining a real-world drivecycle travelled by the vehicle on-road, capturing output torque datafrom the dynamometer resulting from the operating, operating the vehicleand dynamometer respectively according to the output torque data and thereal-world speed schedule to replicate road load experienced by thevehicle during the real-world drive cycle, and operating the vehicleaccording to a real-world shift schedule further defining the real-worlddrive cycle. Real-world emissions data corresponding to the real-worldambient environmental conditions and road load experienced by thevehicle during the real-world drive cycle may be captured. Real-worldenergy efficiency data corresponding to the real-world ambientenvironmental conditions and road load experienced by the vehicle duringthe real-world drive cycle may be captured. Simulated real-worldemissions data in conjunction with the replicated road load experiencedby the vehicle may be captured and the replicated road load may bevalidated by comparing the simulated real-world emissions data to thereal-world emissions data. Real-world energy efficiency data inconjunction with the replicated road load experienced by the vehicle maybe captured and the replicated road load may be validated by comparingthe simulated real-world energy efficiency data to the real-world energyefficiency data. The vehicle test method may further include operatingthe vehicle under simulated ambient environmental conditions andcapturing emissions data, or operating the vehicle under simulatedambient environmental conditions and capturing energy efficiency data.

A vehicle testing laboratory is equipped with either a traditionalchassis dynamometer or, alternatively, a separate axle shaft dynamometerfor each vehicle drive wheel, as well as mass emissions samplingequipment for testing ICE vehicles, where applicable, and a supplementalset of testing equipment for the purpose of exposing a test vehicle to aset of environmental conditions of interest, e.g. ambient temperature,pressure, and humidity, while the vehicle is being tested.

Prior to laboratory testing, a vehicle to be tested is driven on anyroute(s) of interest in the real world, under any environmental andtraffic conditions desired. For example, high traffic arteries in NAAQ“non-attainment areas” might be of particular interest to researchersand regulators. And cold weather fuel economy performance may be ofparticular interest to a manufacturer of vehicle models used moreextensively by customers in colder climates.

During the real world drive(s), a PEMS may be optionally installed onICE equipped vehicles to measure and record mass emissions in grams permile or grams per brake-horsepower-hour, depending on the regulatoryemissions certification requirements for the vehicle. In addition to theoptional emissions data, ambient weather conditions and other testparameters needed to characterize the vehicle operation are alsorecorded, including vehicle speed, accelerator pedal or throttleposition, and brake pedal position or status (i.e. on/off) for theentire test period. For manual transmission vehicles, gear selection andclutch pedal position must also be recorded.

After the real-world testing over the desired route(s), the vehicle isthen brought to the specially-equipped laboratory and either placed onthe chassis dynamometer, or optionally connected to axle-shaftdynamometers (one dynamometer per drive wheel) while the laboratory'smass emissions sampling equipment (in the case of the ICE vehicles)measures mass emissions and the supplemental set of testing equipment isemployed for providing the desired environmental conditions of interestduring vehicle operation, i.e. environmental conditions that may be thesame or may be different from those actually encountered during thereal-world testing.

For the first laboratory test, the full set of real-world testconditions, inclusive of driver interactions and environmentalconditions are reproduced on the chassis dynamometer by controlling thedynamometer speed to replicate the on-road vehicle speed whilesimultaneously controlling the accelerator pedal movement or throttleposition and braking actions to replicate the on-road drive and vehicleresponse. The mass emissions or energy efficiency, depending onpowertrain type, and the dynamometer output (feedback) torque signalthroughout the test are recorded in a normal manner.

If either PEMS emissions data or energy consumption was optionallycollected during the real-world driving, it can then be directlycompared with the laboratory emissions or energy consumption datacollected during the laboratory test under the same conditions to ensurethey are equal, within an acceptable range. This optional “validation”process serves to document a high degree of confidence that both thelaboratory and real-world measurements are both correct andreproducible.

Besides optional validation, the initial dynamometer testing provides anentire torque output history representative of the real-world wheeltorque for the tested vehicle that is a good approximation for the wheeltorque that would be found for the same vehicle in a broad range ofenvironmental conditions when that same vehicle is operated in the sametraffic conditions by the same driver. This real-world torque history,obtained in the laboratory, is then used for “torque matching” insubsequent dynamometer tests performed under different, simulatedambient environmental test conditions. Thus, the principle of “torquematching” makes it possible to accurately and precisely simulate areal-world drive under any ambient conditions of interest, for the samevehicle, speed history, driver effects, and traffic pattern.

“Torque matching” also makes it possible to accurately and preciselysimulate a real-world drive after making other powertrain modifications,e.g. powertrain calibration changes or catalytic converter preciousmetal loadings, and to measure the impact of such modifications to thevehicle's emissions or energy efficiency performance for anymodifications that do not appreciably affect the vehicle's road load.

It should be understood that direct measurement of on-road torque andsubsequent “torque matching” in the laboratory is optional, but requiressubstantially more work preparing a vehicle for testing. For example,specialized “torque wheels” which provide an output torque signal couldbe installed on a vehicle in place of the normal wheels.

After the first laboratory test, ambient conditions, powertraincalibrations, emissions control changes, or other powertrainmodifications can then be made and the test rerun by controlling theaccelerator and brake pedals to reproduce or “match” the torque signalobtained from either a recorded dynamometer torque signal obtainedduring a dynamometer “validation” test or an on-road torque measurement.

Additional tests employing “torque matching” may be performed under asmany different environmental conditions and powertrain changes asdesired to fully characterize the emissions characteristics or energyefficiency of the test vehicle under as wide of a range of environmentalconditions and powertrain configurations as desired.

The “torque matching” and validation method described above causes achassis or powertrain dynamometer to control the speed of the vehicle orengine while providing load on a vehicle powertrain inclusive of aportion of the load caused by the road grade profile of the real-worlddrive. Furthermore, torque matching on a chassis dynamometer can be usedto determine the road grade profile for a first vehicle, which can beused in subsequent laboratory simulations of the same real-world routefor testing the same vehicle or any second vehicle by controlling thedynamometer load in a conventional manner, as a function of vehiclespeed, vehicle acceleration, and road grade. The appropriate dependenceon vehicle speed is often determined using a method known as “coastdowns.” Other methods, including the use of wind tunnels, are alsocontemplated herewith.

To determine the road grade of a driven route profile explicitly, theinitial dynamometer testing of a first vehicle is conducted to provide atorque output history replicating the total real-world wheel torque forthe vehicle as described above. The zero-grade (level road), constantspeed wheel torque and torque needed to accelerate the mass of thevehicle are then calculated for the first vehicle in the usual manner,i.e. as a function of vehicle speed, based on well-known vehiclecoast-down procedures, and accelerations based on the mass of thevehicle.

The difference between the total real-world wheel torque measured by thedynamometer and the sum of the zero-grade, constant speed wheel torqueand the torque needed to overcome the vehicle inertia is calculated forthe entirety of the real-world route to be simulated in the laboratory.This difference is the resultant, additional load on the first vehicledue to the effect of the road grade ofthe real-world route. Basicprinciples oftrigonometry are subsequently applied to determine thecorresponding road grade profile causing the additional load on thefirst vehicle.

The resultant road grade profile of the real-world drive is vehicleindependent. It is useful to determine this profile with any vehicle andthen use the profile in subsequent laboratory dynamometer tests for thesame vehicle or any other vehicle for simulating the original real-worlddrive, or parts of the original real-world drive, by programming thedynamometer load as a function of vehicle ground speed, vehicle airspeed, vehicle acceleration, and/or road grade, as modern dynamometersare typically capable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows various vehicle, driving, and traffic conditions thataffect the emissions and/or the energy efficiency of a vehicle.

FIG. 2 shows a vehicle being tested in the real world for obtaining aset of measurements sufficient for reproducing the test in a testinglaboratory, and optionally to collect actual on-road emissions and/orenergy efficiency data.

FIG. 3 shows how dynamometer torque is obtained for subsequentlaboratory testing purposes and how optional “validation” testing isperformed using an environmental chamber.

FIG. 4 shows a test arrangement used to simulate real-world driving andto collect simulated real-world emissions data from a vehicle using achassis dynamometer in an environmental chamber.

FIG. 5 shows how dynamometer torque is obtained for subsequentlaboratory testing purposes and how optional “validation” testing isperformed using an environmental condition simulator in place of anenvironmental chamber.

FIG. 6 shows a test arrangement used to simulate real-world driving andto collect simulated real-world emissions data from a vehicle using anenvironmental condition simulator.

FIG. 7 shows how dynamometer torque is obtained for subsequentlaboratory testing purposes and how optional “validation” testing isperformed using axle shaft dynamometers.

FIG. 8 shows a test arrangement used to simulate real-world driving andto collect simulated real-world emissions data from a vehicle usingaxle-mounted dynamometers.

FIG. 9 is a flowchart illustrating an example overall process or testmethod.

FIG. 10 shows an air speed measurement system suitable for accuratelymeasuring the air speed of a vehicle as it travels on a road.

FIG. 11 shows the overall process of obtaining road grade informationfrom a real-world road test and using the road grade information forsubsequent laboratory dynamometer simulations of a real-world drive.

DETAILED DESCRIPTION

Various embodiments of the present disclosure are described herein.However, the disclosed embodiments are merely exemplary and otherembodiments may take various and alternative forms that are notexplicitly illustrated or described. The figures are not necessarily toscale; some features may be exaggerated or minimized to show details ofparticular components. Therefore, specific structural and functionaldetails disclosed herein are not to be interpreted as limiting, butmerely as a representative basis for teaching one of ordinary skill inthe art to variously employ the present invention. As those of ordinaryskill in the art will understand, various features illustrated anddescribed with reference to any one of the figures may be combined withfeatures illustrated in one or more other figures to produce embodimentsthat are not explicitly illustrated or described. The combinations offeatures illustrated provide representative embodiments for typicalapplications. However, various combinations and modifications of thefeatures consistent with the teachings of this disclosure may be desiredfor particular applications or implementations.

The use of PEMS has made it clear that current laboratory-based testingprotocols often do not accurately characterize the emissions performanceor energy efficiency (fuel economy) of a vehicle operating in the realworld, and over a broad range of the relevant factors listed abovebecause of the high cost and significant effort required in conductingrepresentative laboratory testing. Similar testing limitations for BEV'sexist, limiting a full understanding of energy efficiency for thosevehicles operating in the real world at lower ambient temperatures andunder real-world driving conditions.

In some examples, is an apparatus and a method for collecting accurate,real-world emissions and energy efficiency test data for any vehicle inan accurate and repeatable manner, over a broad range of environmentalconditions not normally reproduced in a laboratory environment arecontemplated. The following description shows how a testing laboratorycan be used to accurately simulate real-world conditions for anarbitrary vehicle and for any combination of environmental conditionsdesired. In this way, compliance with emissions and energy efficiencystandards can be assured by regulators and the effects of changes to avehicle's powertrain or powertrain calibration can be accuratelydetermined by automobile manufacturers to efficiently achieve emissionscompliance and maximize fuel economy to their customers.

The testing method described above could employ other vehicle operatingparameters as surrogates for the use of throttle position in real-worlddriving and/or for the use of torque for controlling the dynamometer.For example, fuel flow rate, fuel injector pulse width, and powertraincomputer calculations for calculating powertrain torque during vehicleoperation are analogous to throttle position or torque for subsequentvehicle or dynamometer control under the same real or simulatedenvironmental conditions for laboratory testing.

Specific embodiments are discussed below. But the method of testing maybe essentially the same, independent of the apparatus employed. Itshould be understood that these specific embodiments are forillustrative purposes only and that there is much wider applicabilitythan this or any other single embodiment. All such embodiments arecontemplated herewith.

FIG. 1 shows many of the numerous factors that affect tailpipe emissionsof vehicles with ICEs as well as the energy efficiency and operatingrange of all vehicles in the real world. The factors are related tovehicle design, the interactions of the vehicle with its environment(ambient temperature, pressure, humidity, road grade, trafficconditions), driving style (speeds, acceleration rates, braking habits),and the use of driver-selectable options.

FIG. 2 shows an arbitrary vehicle 1 being tested in the real world. Foran ICE powertrain, real-world tailpipe 20 emissions and fuel economydata (19 collectively) are optionally collected continuously from anon-board PEMS 4 in the case of an ICE vehicle 1, or energy consumptionand efficiency measurements are optionally collected continuously from aBEV powertrain. While the emissions and fuel economy data or the energyefficiency data from the real-world test is very useful by itself forevaluating the emissions or energy efficiency performance of thevehicle, it is only a narrow view or “slice” of the overall real-worldperformance of the vehicle 1 under generalized conditions. This isbecause any given test is done under a very specific set of testconditions encountered during any single real-world test. Someembodiments provide a means and method for leveraging what is learnedfrom a relatively small number of real-world tests to enable accurateand repeatable simulations of the same vehicle under a broad range ofenvironmental and powertrain design conditions and to collectrepresentative emissions and fuel economy data over that broad range ofconditions.

More specifically, the main purpose of the real-world road testingcomponent is two-fold. First, to optionally obtain emissions and/orenergy efficiency data for later use in validating laboratorysimulations of the same real world environmental conditions. Secondly,for obtaining data that is sufficient for accurately determining thetorque that was applied to the driven wheels throughout the entirereal-world test, without the use or installation of specialized “torquewheels” 58 or other torque measurement devices. Of course, the “torquewheel” measurements could also be optionally used.

By determining (or directly measuring) the real-world test torqueschedule, the same torque schedule can be applied to the driven wheelswhile the modified or unmodified vehicle is connected to a chassisdynamometer under the same, or optionally different environmentalconditions, subsequently simulated in a testing laboratory.

The real world test route is chosen by the researcher for his or herpurposes. For example, it may be a high traffic volume, light-dutypassenger car commuter corridor during rush hour, or may be along-duration route inclusive of a number of sub-routes that are eachhigh volume commuter corridors, or may be any other route of interest toeither regulators or automobile manufacturers. Or the test route may beone that is more applicable to heavy-duty vehicles that employheavy-duty engines that are traditionally tested on an enginedynamometer for regulatory purposes.

Referring to FIG. 2, the vehicle 1 is driven on the road 2 in either anormal driving manner or in a manner consistent with the specifictesting goals. For example, the aggressiveness of the driver could be atesting condition to test the robustness of the emissions controlsystem. And driver-selectable options including, but not limited to airconditioning, and “sport” vs. “economy” driving mode are chosen asdesired, consistent with research purposes, for the real-world test.Driver selections are recorded for subsequent reproduction in laboratorytesting.

For the entire duration of the real-world testing, a vehicle speedsignal 16, an accelerator pedal position or throttle position signal 18,a driver's braking actions or braking effort signal 20, a clutch pedalposition signal 21, and a gear selection signal 55 are all recorded atappropriate frequencies, e.g. 50-100 Hz for the vehicle speed,accelerator pedal or throttle position, clutch and braking effortsignals. CAN bus signals are ideal for this purpose if they can beobtained at a sufficient frequency, otherwise, forelectronically-controlled powertrains, the signals can be obtainedeasily by directly sensing signals at the appropriate wiring harnesslocations. Other data logging means that are commonly used can also beemployed.

There are many other ways of recording vehicle speed, each with its ownadvantages and disadvantages. For example, use of the vehicle's owntoothed-wheel speed sensors for modern vehicles, accessible via thevehicle's CAN bus is a convenient way. If it is not accessible by theresearcher, or is not available at approximately 50-100 Hz or higher, orif it is desirable to perform the speed measurements without the needfor connecting to the vehicle's CAN bus, e.g. for older vehicles, othermethods may be employed.

GPS is commonly used on PEMS but the speed may not be updated at a highenough frequency and small speed changes at a high update rate may bedominated by measurement uncertainty.

Road surface radar systems, mountable on the test vehicle is anotheroption for obtaining vehicle speed with a high update rate, but likeGPS, small speed changes may be obscured by errors introduced byvertical motion of the vehicle. And the system may have to be calibratedif the angle of incidence to the road is vehicle-dependent.

Another method for determining vehicle speed at high frequency is byemploying a remote optical sensor, more specifically a retro-reflectivesensor in which both the transmitter and receiver are located in thesame housing and the light beam is reflected from a reflective surfaceapplied to the moving part. In the present case, a reflective paint orsticker is applied to one of the vehicle's tires and the sensor isclamped to a control arm of the vehicle 1 suspension which is stationaryrelative to the location of the tire. The output frequency from thespeed sensing means is equal to the rotational frequency of the tire andproportionate to the speed of the vehicle, the constant ofproportionality easily determined in known ways.

An onboard “weather station” provides a continuous update 30 of ambientatmospheric conditions from which atmospheric pressure, temperature,humidity, and air speed measurements are all recorded at an appropriatefrequency, e.g. 1 Hz.

For an ICE vehicle 1, a PEMS 4 may be optionally used to collectreal-world tailpipe emissions and fuel economy (by carbon balancetechnique) data 19 for the road test, or other means, e.g. a fuel flowmeter (not shown) may be used to obtain optional fuel consumption data.For a BEV vehicle 1, electrical power consumption is optionally recordedover the entire real-world drive using electrical means commonly used inthe field (not shown).

FIG. 3 shows a first embodiment of a laboratory testing apparatuswhereby the vehicle 1 that was previously tested in the real-world, asillustrated in FIG. 2, is subsequently tested in a laboratory equippedwith an electric chassis dynamometer 10, located in a temperature,pressure, and humidity controlled environmental chamber 50, as shown inFIG. 3. As apparent to those of ordinary skill, the techniques describedwith reference to the figures for vehicle testing on a chassisdynamometer of course apply to powertrain testing on an enginedynamometer, etc.

The chassis dynamometer 10 is set to be controlled in “speed mode,” i.e.the speed of the dynamometer rolls 12 are controlled by commanding thedesired roll 12 speed as a function of time using the desired vehicle 1speed as a control signal 16. While the vehicle 1 turns the dynamometerrolls 12, or resists the turning of the dynamometer rolls 12, a dynamictorque output signal 17 from the dynamometer control panel 11,indicative of the torque applied by the vehicle 1 to the dynamometerrolls 12 is also monitored and recorded using a recording means (notshown).

A robotic driver 13 commonly used in the field or alternatively, ananalogous electronic signal driving control means (not shown) is alsoemployed. The robotic driver 13 may be more appealing to the researcherwhen electronic interfacing with the vehicle is not possible or notdesired. For example, the electronic signal means may be more appealingto a vehicle manufacturer or supplier when there is unlimited access tothe necessary information for interfacing with the electronic controls.The robotic driver 13 is able to control the accelerator pedal, brakepedal, clutch pedal, and gear selection lever of the vehicle 1programmatically and with proper coordination. Or direct-electronicsignal control means, when applicable, can be used to affect the sameresult.

The vehicle 1 is placed on the electric dynamometer rolls 12 in thenormal manner for laboratory emissions and/or energy efficiency testing.The dynamometer 10 could have any number of independent rolls, up to oneroll per vehicle tire. The temperature, pressure, and humidity controls(not shown) of the environmentally-controlled test cell chamber 50 areall set to the desired values or placed under programmatic control tomaintain a changing set of values for the intended test conditions. Forexample, dynamic programmatic control may be desirable to recreate thechanging environmental conditions experienced on a previous real-worldtest, especially if the real-world test was done in varying altitudes.In the case of a BEV, it may be sufficient to control only thetemperature of the environmental test cell chamber 50 to a desired fixedtemperature or employ a dynamic temperature schedule.

A large, variable speed fan 15 is used to simulate air flow under andaround the vehicle 1, or alternatively, a smaller variable-speed fan maybe used to provide cooling to the radiator(s) of the vehicle 1. A largefan capable of simulating dynamic on-road airflows may be preferable forcold-start tests, especially for a vehicle 1 employing a catalyticconverter 56, so a real-world cooling effect is reproduced. In eithercase, the speed of the cooling air is ideally controlled to, or inproportion to the real-world air speed, or the dynamometer roll 12speed, to simulate on-road air speeds captured with the weather station.

The 100 Hz vehicle speed data 16 schedule previously recorded during thereal-world driving is used to control the dynamometer 10 speed duringthe laboratory testing.

The atmospheric conditions 30 measured during the real-world test aresimulated using the environmental test chamber 50. For a BEV vehicle 1,it may be sufficient to control only the test cell temperature. Theenvironmental conditions may be fixed values when appropriate, or may beprogrammatically coordinated with the vehicle speed and other vehicleparameters so they properly correspond with the vehicle operation thatwas recorded during the real-world test as previously shown in FIG. 2.

The dynamometer roll 12 speed is then controlled using the recordedvehicle speed 16 from the real-world drive while the accelerator pedalor throttle position, braking action or effort, clutch pedal, and thetransmission gear selector, in the case of a manual transmission, areall controlled to the same positions or values 35 that were obtainedduring the real-world drive, as shown in FIG. 2. Additionally, thosecontrols, the dynamometer speed, and the other simulated conditions, areall synchronized properly in time, to precisely mimic the conditionsexperienced during the real-world test. In this way, the torque appliedby the vehicle 1 tires to the dynamometer rolls 12 is caused to match,to a very close approximation, the torque that the same vehicle 1 hadpreviously applied to the road surface 2 during the real-world test.

The output dynamometer torque signal 17 is recorded from the dynamometercontrol panel 11 for use in subsequent testing that will take placeunder different, simulated environmental conditions.

Standard laboratory emissions measurement sampling 14 or optionally PEMSemissions measurement equipment 4 is employed to measure mass emissionsdata in the usual manner for ICE vehicles 1, and energy consumptionmeasurements are made in the usual manner for BEV vehicles 1.

If PEMS data 19 or energy consumption data was optionally recordedduring the real-world drive (FIG. 2), it may be desirable for the firstlaboratory test to also serve as a “validation” test as shown in FIG. 3.For purposes of validation, the laboratory-measured emissions and energyefficiency data can be compared to the analogous results optionallyobtained during the actual real-world test to demonstrate the degree ofvalidity of the testing and method in relation to a set of acceptancecriteria.

Referring to FIG. 4, subsequent dynamometer tests can then be conductedfor the purpose of evaluating or demonstrating the emissions and/orenergy efficiency of the same vehicle operating on the same route, withthe same traffic conditions, etc., but with different environmental orambient conditions. Or subsequent testing can be for the purpose ofevaluating design changes to the vehicle 1 or the vehicle's emissionscontrol system, changes to the powertrain calibration, or any changes tothe vehicle 1 that do not significantly affect the road load of thevehicle 1.

To conduct such additional tests under different conditions than thereal-world test, the dynamometer 10 is once again controlled in “speedmode.” But the vehicle 1 accelerator pedal or throttle position iscontrolled differently. Rather than mimic the real-world acceleratorpedal position or movement 18 as above, the accelerator pedal orthrottle position is controlled by the robotic driver 13, or by directelectronic means, using a feedback loop. The feedback signal for thefeedback loop is the output dynamometer torque signal. The dynamicsetpoint or dynamic target value to be achieved is the torque schedule17 that was recorded from the dynamometer control panel 11 during thesimulated real-world testing described above. By controlling the vehiclein this way, it is possible to evaluate the effect on emissions and/orenergy efficiency of a vehicle 1 caused by changes made to the vehicle 1or by changes caused by operating the same vehicle 1 on the same routeunder the same traffic conditions, but under different environmentalconditions as desired. Additional testing can also be done afterintroducing any desired changes to the vehicle 1 itself (changes that donot significantly affect road load).

Using this new testing method, a single road test performed over a verylimited range of temperatures, pressures, and humidity values can beused to enable as many laboratory tests as desired for characterizingthe emissions and/or energy efficiency performance of the same vehicle 1over a wide range of ambient conditions and vehicle design changes.Because the testing is conducted in a laboratory, it can be done in avery repeatable manner. And the effect of changes to emissions controlsor powertrain calibrations that do not significantly affect the roadload of the vehicle can be evaluated by conducting repeat testing beforeand after such changes are made.

Repeat tests under different, desired atmospheric test conditions areconducted as above to understand the emissions and/or energy efficiencyof the vehicle 1 under a wide range of environmental conditions.

Additionally, if it is not necessary to conduct “validation” tests, theequipment needed for the real-world testing is simply a data logger anda means for measuring the various pedal positions or pedal effortsapplied by the driver.

A second embodiment for testing ICE equipped vehicles is shown in FIG.5. An “environmental conditions simulator” 57, recently made availableby emissions testing equipment manufacturers is employed, rather thanemploying a more capital intensive environmental testing chamber. Thisallows the use of a standard emissions test cell 51. The ambient airconditions are simulated by the environmental conditions simulator 57which is also moveable and can be shared with other test cells. Thesimulator 57 is connected to the vehicle 1 intake air system of thevehicle's engine 3 by the intake air hose 26 and to the vehicle'stailpipe 20 by the exhaust gas hose 27, whereby the simulator 57controls the intake air pressure and the exhaust backpressure to eitherfixed, selected values, or to programmatically controlled, dynamicvalues to mimic the conditions recorded 30 (FIG. 2) during thereal-world test, properly synchronized with the dynamometer roll 12speed. The humidity of the intake air is also controlled and either thePEMS emissions measurement system 4 or standard laboratory emissionsmeasurements 14 are made to document the emissions and fuel economyperformance of the vehicle under the simulated environmental conditions.

Testing with the environmental simulator 57 is conducted in the samemanner described above. A variable speed fan 25 provides powertraincooling and is controlled using either the vehicle ground speed or,preferably, with the measured wind speed that was recorded using theweather station during the on-road drive.

Once again, the first laboratory test may serve as a validation test, ormay be to simply capture a torque schedule 17 that is representative ofthe associated real-world road load torque to be used for subsequenttesting under different, simulated environmental conditions, or aftervehicle 1 design changes are made.

Referring to FIG. 6, repeat tests under different environmental and/orvehicle design test conditions are conducted as described above to helpunderstand the emissions and/or energy efficiency of the vehicle 1 undera wide range of environmental and design conditions. The previouslycaptured torque schedule 17 associated with the real-world road load isused as the reference signal, in conjunction with the output dynamometertorque 44 used as a feedback signal, to control the throttle, employingthe robot driver 13 as the actuator for the torque feedback loop.

FIG. 7 shows yet another embodiment of the apparatus. It is similar tothe embodiment shown in FIG. 5, except for the use of drive axledynamometers 34, 35 in place of the chassis dynamometer 10 anddynamometer rolls 12 used in FIG. 5. Specialized wheels 32,33 thatemploy lockable hub bearings 50, 51 are used to allow the drive axleshafts 45, 46 to freely rotate within the wheels to drive thedynamometer input shafts 36, 37 when they are set to the “unlocked”positions. When they are set to the “locked” positions, the drive axleshafts drive the specialized wheels 32, 33 in a normal manner so thevehicle can be driven and moved to the desired location for testing.

During a test, the rotational speeds of the dynamometers 34, 35 arecontrolled at the appropriate rotational frequency corresponding to thereal-world vehicle speed 16 being simulated, with respect to thediameter of the wheels used during the prior real-world test.

Otherwise, testing is conducted in the same manner as described above.After a real-world test as shown in FIG. 2 is conducted, the vehicle 1control pedal positions 35 from the real-world test are used to controlthe vehicle while the real-world test ambient conditions are simulatedwith either an environmental chamber 50 or an environmental conditionsimulator 57. The dynamometers' 34, 35 torques 17 (two signals) arerecorded and the emissions are optionally measured and used in the samemanner as describe above for validation, if desired.

FIG. 8 shows how subsequent laboratory testing is done using the driveaxle dynamometers 34, 35. The simulated ambient conditions are changedto other desired values of interest, using either the environmentallycontrolled chamber 50 housing the test cell or an environmentalsimulator 57 as described above. Rather than control the acceleratorpedal to achieve the same pedal positions during the real-world test,the accelerator pedal is controlled with the robot driver 13 to achievethe same torque schedule 17 that was recorded from the dynamometers 34,35 during the initial laboratory or validation test and using a feedbackloop as described above. Exhaust missions and/or energy efficiencyparameters are measured and recorded during testing for validationpurposes, if they were collected during the real-world driving.Otherwise they are compared with the original laboratory testing resultsto gauge the effect of whatever changes were made to the simulatedenvironmental conditions or vehicle design.

The embodiment shown in FIG. 7 and FIG. 8 may be most useful forconducting representative “real-world” emissions and energy efficiencytesting of vehicles and machines that employ internal combustion enginesor driveline components that have been certified to meet engine orcomponent emissions or efficiency standards, rather than vehicleemissions or efficiency standards.

The testing process for collecting a limited amount of real-worlddriving data and using that data to obtain a real-world torque scheduleto subsequently simulate real-world driving in the laboratory isdescribed above and shown in FIG. 9. Collecting PEMS or energyefficiency data during the real-world drive allows the real-world driveto also be used for test validation purposes.

By collecting real-world vehicle 1 data and using the data inconjunction with one of the apparatuses and method described above, theemissions and/or energy efficiency ofa vehicle 1 (or portion thereof)can be characterized under a wide range of environmental conditions.Effects on the emissions performance or the energy efficiency of avehicle (or portion thereof) caused by changes to the vehicle design(changes that do not affect the road load of the vehicle) can also beassessed via dynamometer (e.g., chassis dynamometer, engine dynamometer,etc.) as suggested above for any desired route or set of real-worldtraffic conditions.

The method described above causes a dynamometer to implicitly reproducethe totality of the real-world load or torque on a vehicle powertrainfrom all causes including vehicle acceleration, aerodynamic drag forces,road surface to tire friction, drivetrain losses, and the road gradeprofile of the real-world drive of the same vehicle.

Alternatively, the “torque matching” process can be used to estimate theroad grade of a real-world drive conducted by a first vehicle, asdescribed above, i.e. it can be used to explicitly determine the roadgrade profile of the entire real-world drive route or selected portionsof the real-world drive route. Furthermore, by installing a wind speedmeasurement device prior to the road drive and by collecting wind speeddata during the drive, more accurate road grade estimates can beobtained, and more accurate dynamometer simulations of the real-worldload can be performed. Once this is accomplished, a dynamometer can becontrolled in a normal manner to accurately simulate the loading due toroad load, time dependent atmospheric wind forces, instantaneous roadgrade, and inertial forces.

FIG. 10 shows a wind measurement system for detachably mounting on anexternal vehicle surface 107 of a vehicle body. The ultrasonic windmeter 101 is capable of measuring both wind speed and direction whenproperly mounted on the vehicle, as the vehicle moves through theatmosphere. The meter 101 is held away from the vehicle surface 107 bythe support structure 104, in a displaced position where the air motionis relatively unaffected by the presence of the moving vehicle andoriented, using the articulating friction joint 103 for adjusting theorientation of the mounting platform 102 for this purpose. The pneumaticsuction mount platform 105 detachably fixes the system to the vehiclesurface 107. The data/coms cable 106 carries electronic signals from thewind meter 101 indicating the instantaneous wind speed and winddirection to a remote data acquisition system (not shown).

By first replicating and recording the totality of real-world forcesacting on a vehicle driven on the road (FIG. 2) using a dynamometer, thereal-world road grade profile and actual wind speeds experienced by afirst vehicle 1 operating on the road can then be used for subsequentrealistic laboratory simulations of either the same real-world driveroute for the same vehicle, or for the same real-world drive route forany second vehicle for which standard road load coefficients are eitherknown or can be determined.

Controlling the dynamometer 10 with the resultant road grade controlparameter combined with the appropriate road load simulation parameterscommonly used for dynamometer load control to simulate vehicleaccelerations, tire friction and drivetrain losses as a function ofvehicle speed, as well as aerodynamic forces as a function of air speedresults in a realistic simulation of the load on the powertrainassociated with the real world drive or portion of the real world drivefor an arbitrary vehicle.

To determine the real-world road grade profile explicitly from a realworld drive of a first vehicle 1, the initial dynamometer 10 testing ofthe first vehicle 1 is, as described above, conducted to provide a totaltorque output history array [T], considering each drive wheel or axle,representative of the total real-world torque history experienced by thevehicle wheels or axles when driven on the road as described above. Theassociated total force, expressed as an array, and acting on the vehiclecan be denoted [F].

The zero-grade (level road) condition total tractive force is thencalculated for the first vehicle 1 over the real-world vehicle (ground)speed 16 cycle in the usual manner known in the art of dynamometer roadload control for emissions compliance purposes, as a function of vehiclespeed, based on the well-known vehicle coast down procedures fordetermining vehicle-specific road load factors (A, B, and Ccoefficients) for characterizing the tractive force comprising rollingresistance and aerodynamic drag.

The general tractive force applied by a chassis dynamometer roll 12 to atest vehicle tire as a function of time is often expressed as

$\begin{matrix}{{F(t)} = {( {A + {B*{v(t)}} + {C*{v(t)}^{2}}} ) + {M*\frac{{dv}(t)}{dt}} + {M*g*\sin \; {\alpha (t)}}}} & \lbrack {{Equation}\mspace{14mu} 1} \rbrack\end{matrix}$

where A, B, and C are the zero-grade road load coefficients normallydetermined using a coast down procedure, v(t) is the ground speed of thevehicle as well as the speed of the vehicle through the surrounding air,i.e. terrestrial wind speeds are ignored, M is the mass of the vehiclewhich can be determined by measuring vehicle weight, g is thegravitation acceleration constant, e.g. 9.81 m/s², and α(t) is the angleof inclination of the road as a function of time, where

${{Road}\mspace{14mu} {Grade}\mspace{14mu} {G(t)}} = {\frac{\Delta \mspace{14mu} {vehicle}\mspace{14mu} {elevation}}{\Delta \mspace{14mu} {vehicle}\mspace{14mu} {horizontal}\mspace{14mu} {displacement}} = {\tan \mspace{14mu} {\alpha (t)}}}$

But in the real world, the aerodynamic drag acting on the vehicle 1 alsodepends upon the speed and direction of terrestrial winds, as well asthe surrounding air density, which is related to both air pressure andtemperature 30. These additional effects can be taken into account forthe purpose of providing a more accurate replication of real-worldforces acting on the vehicle during a road drive. A more generaltreatment of the tractive force that a chassis dynamometer needs toimpart on a test vehicle to accurately simulate real-world forces,considering the aforementioned effects, is given by

$\begin{matrix}{{F(t)} = {( {A + {B*{v_{g}(t)}} + {{\rho (t)}\text{/}\rho_{0}*C*{v_{a}(t)}^{2}}} ) + {M*\frac{{dv}_{g}(t)}{dt}} + {M*g*\sin \; {\alpha (t)}}}} & \lbrack {{Equation}\mspace{14mu} 2} \rbrack\end{matrix}$

where A, B, and C are the road load coefficients first determinedthrough the normal coast down procedure as described above, andconducted at a measured atmospheric temperature and pressure condition,i.e. at a known air density ρ₀, ρ(t) is the actual air density throughwhich the on-road vehicle moves, determined by atmospheric airtemperature, pressure, and humidity measurements, v_(g)(t) is the groundspeed of the vehicle as a function of time measured by any means,including but not limited to an on-board GPS receiver, the vehicle's CANbus signals, or the vehicle's On-Board Diagnostics port data stream, andv_(α)(t) is the airspeed of the vehicle as a function of time measuredwith the on-board air speed measurement device.

Equation 2 can be written alternatively as

$\begin{matrix}{{F(t)} = {( {A + {B*{v_{g}(t)}} + {{C(t)}*{v_{a}(t)}^{2}}} ) + {M*\frac{{dv}_{g}(t)}{dt}} + {M*g*\sin \; {\alpha (t)}}}} & \lbrack {{Equation}\mspace{14mu} 3} \rbrack\end{matrix}$

showing C as a time varying function, incorporating the influence ofchanging air density. C(t) is equal to the constant C from the coastdown procedure whenever the air density is equal to the densitycondition during which it was originally determined using thatprocedure, but is otherwise corrected as a function of time to accountfor the variable effects of changes of real-world air density conditionsover time as the vehicle operates in a dynamic environment exhibitingdifferent atmospheric temperatures, pressures, and humidities, some ofwhich result from changes in altitude.

Referring to FIG. 10, v_(α)(t) can be measured directly using a windspeed indicator, e.g. the ultrasonic wind meter 101 mounted on thesurface 107 of a vehicle 1 body during the on-road testing as shown. Fordynamometers not capable of being controlled with a dynamic Ccoefficient, or not capable of being controlled with separate groundspeed and air speed values, F(t) can be expressed in the convenient,alternative form

$\begin{matrix}{{F(t)} = {( {A + {B*{v_{g}(t)}} + {C*{v_{g}(t)}^{2}}} ) + {M*\frac{{dv}_{g}(t)}{dt}} + {M*g*\sin \; {\alpha^{\prime}(t)}}}} & \lbrack {{Equation}\mspace{14mu} 4} \rbrack\end{matrix}$

whereby a modified road grade parameter α′(t) represents a modified roadgrade, more specifically, the actual road grade modified to account forthe real-world wind load effects whenever the vehicle and wind speedsare not equal in magnitude. Of course, F(t) could also assume any otherform desirable for use by the test engineers and other mathematicalprocedures for calculating the force on a moving vehicle are alsocontemplated.

Alternatively, if the A, B, C coefficients, vehicle ground speed,vehicle mass, and road grade are all known values, then the vehicle airspeed can be determined from Equation 3. Or, if the A, B, Ccoefficients, vehicle ground speed, vehicle mass, and vehicle air speedare all known or measured, and the road grade is determined as describedbelow, explicit wind load information can be derived by the differencein the calculated values of F(t) by first calculating F(t) using the airspeed in accordance with Equation 3, then calculating F(t) bysubstituting ground speed for air speed, i.e. substituting v_(g)(t) forv_(α)(t), and then subtracting the two values. Hence, wind loadinformation can be derived from the test schedule torque outputsgenerated by a dynamometer. Similarly, by knowing or measuring vehicleground speed, air speed, and road grade from a real road drive,representative A, B, C road load coefficients, or equivalent, can bedetermined using a dynamometer and applying Equation 3. This method fordetermining the road load coefficients eliminates the need forperforming a separate coast down procedure which can be laborious andtime consuming. And if the real road drive is conducted on a level road,Equation 3 is simplified by eliminating the road grade term altogether.

The general tractive dynamometer torque applied by the chassisdynamometer rolls to a test vehicle's tires, or by axle dynamometers 34,35 to a test vehicle's axles, is given by

T(t)=F(t)*R

in the case of a dynamometer roll, where R is the radius of the circularroll, and alternatively, T=Tshaft for the case of an axle shaftdynamometer.

Therefore, the zero-grade chassis dynamometer tractive force applied toa vehicle under varying simulated wind conditions, i.e. F0(t) forα(t)=0, can be calculated by

$\begin{matrix}{{F\; 0(t)} = {( {A + {B*{v_{g}(t)}} + {{C(t)}*{v_{a}(t)}^{2}}} ) + {M*\frac{{dv}_{g}(t)}{dt}}}} & \lbrack {{Equation}\mspace{14mu} 5} \rbrack\end{matrix}$

Equation 5 takes into account the forces due to road load, wind speeds,and vehicle inertia, but not road grade. Alternatively, Equation 5 couldbe represented as a time-series array [F0], where [F0]=[T0]/R in thecase of a chassis dynamometer roll 12 of radius R.

The difference between the total real-world tractive force replicated bythe dynamometer 10 and applied to the vehicle, as determined by theinitial dynamometer test output torques 17 for each wheel or axle of afirst vehicle 1, and the zero-grade tractive force as calculated for theentirety of the real-world drive cycle to be simulated in the laboratoryis equal to the resultant, additional load on the vehicle 1 due to theeffects of the road grade of the real-world route and the mass of thevehicle 1 and is given by

${{\lbrack F\rbrack - \lbrack {F\; 0} \rbrack} = {{{\lbrack T\rbrack \text{/}R} - \lbrack {F\; 0} \rbrack} = {M*g*\lbrack {\sin \; \alpha} \rbrack}}},{\lbrack {\sin \; \alpha} \rbrack = {( {\frac{\lbrack T\rbrack}{R} - \lbrack {F\; 0} \rbrack} )\text{/}( {M*g} )}},{{{and}\lbrack\alpha\rbrack} = {\arcsin \lbrack {( {\frac{\lbrack T\rbrack}{R} - \lbrack {F\; 0} \rbrack} )\text{/}( {M*g} )} \rbrack}}$

where [α] is the angle of inclination of the road traversed by vehicle 1in the real world. The road grade [G] can then be expressed as, andcalculated by

[G]=[tan α]=[sin α/cos α]=[sin α/(1−sin 2α){circumflex over ( )}½*100%

The resultant road grade profile [G], representative of the actual roadgrade of the route traveled by the first vehicle in the real world, andthe mass M of any vehicle, are then used in subsequent laboratorydynamometer tests for any vehicle in simulating the original real worlddrive (FIG. 1) for that vehicle, or parts of the real-world drive, byeffectively programming the dynamometer load as a function of vehicleground speed, vehicle air speed to account for winds, using theappropriate A, B, and C coefficients determined by a coast down or othermethod, correcting the coefficients for the effects of air density, andaccounting for the road grade, as described above.

Using the above methodology, the dynamometer 10 can be programmed tosimulate the appropriate load on any vehicle virtually driven over thesame road route (FIG. 1), under any atmospheric or wind conditions byfirst determining appropriate A, B, and C coefficients using standardcoast down procedures, calculating C(t) by correcting C for the variableair temperatures and pressures being simulated along the route,calculating v_(α)(t) based on the ground speed of the vehicle and windconditions to be simulated, and finally by programming the dynamometercontroller with the set of parameters, including A, B, C(t), v_(g)(t),and v_(α)(t), or their equivalents, depending on the manner in which aparticular dynamometer 10 is programmed. This process is shown in FIG.11.

Exhaust emissions, fuel economy, or energy efficiency can be measured inthe laboratory, in the manner described above, while any of theaforementioned laboratory tests are conducted. Measuring the exhaustemissions of a vehicle on simulated drives using the laboratorydynamometer 10 before and after making changes to the vehicle is aneffective way of assessing the impact of the changes on the emissions orenergy efficiency performance of the vehicle.

The processes, methods, or algorithms disclosed herein can bedeliverable to/implemented by a processing device, controller, orcomputer, which can include any existing programmable electronic controlunit or dedicated electronic control unit. Similarly, the processes,methods, or algorithms can be stored as data and instructions executableby a controller or computer in many forms including, but not limited to,information permanently stored on non-writable storage media such asRead Only Memory (ROM) devices and information alterably stored onwriteable storage media such as floppy disks, magnetic tapes, CompactDiscs (CDs), Random Access Memory (RAM) devices, and other magnetic andoptical media. The processes, methods, or algorithms can also beimplemented in a software executable object. Alternatively, theprocesses, methods, or algorithms can be embodied in whole or in partusing suitable hardware components, such as Application SpecificIntegrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs),state machines, controllers or other hardware components or devices, ora combination of hardware, software and firmware components.

The words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the disclosure andclaims.

As previously described, the features of various embodiments may becombined to form further embodiments that may not be explicitlydescribed or illustrated. While various embodiments may have beendescribed as providing advantages or being preferred over otherembodiments or prior art implementations with respect to one or moredesired characteristics, those of ordinary skill in the art recognizethat one or more features or characteristics may be compromised toachieve desired overall system attributes, which depend on the specificapplication and implementation. These attributes include, but are notlimited to cost, strength, durability, life cycle cost, marketability,appearance, packaging, size, serviceability, weight, manufacturability,ease of assembly, etc. As such, embodiments described as less desirablethan other embodiments or prior art implementations with respect to oneor more characteristics are not outside the scope of the disclosure andmay be desirable for particular applications.

What is claimed is:
 1. A test method comprising: deriving road gradeinformation from test schedule torque outputs generated by a dynamometeroperatively arranged with a first vehicle; and controlling anaccelerator pedal, an accelerator pedal signal, a fuel injector, amanifold pressure, a motor controller, or a throttle valve associatedwith the first or a second vehicle according to a speed schedule suchthat the dynamometer, or another dynamometer, programmed with the roadgrade information and operatively arranged with the first or secondvehicle applies a load to the first or second vehicle that reflects theroad grade information.
 2. The test method of claim 1 further comprisingmeasuring emissions of the first or second vehicle during thecontrolling.
 3. The test method of claim 1 further comprising changing acalibration of the first or second vehicle after the controlling, andagain controlling the accelerator pedal, accelerator pedal signal, fuelinjector, manifold pressure, motor controller, or throttle valveaccording to the speed schedule such that the dynamometer, or theanother dynamometer, programmed with the road grade information andoperatively arranged with the first or second vehicle applies a load tothe first or second vehicle that reflects the road grade information. 4.The test method of claim 3 further comprising measuring emissions of thefirst or second vehicle during the again controlling.
 5. The test methodof claim 1 further comprising changing ambient conditions of the firstor second vehicle after the controlling, and again controlling theaccelerator pedal, accelerator pedal signal, fuel injector, manifoldpressure, motor controller, or throttle valve according to the speedschedule such that the dynamometer, or the another dynamometer,programmed with the road grade information and operatively arranged withthe first or second vehicle applies a load to the first or secondvehicle that reflects the road grade information.
 6. The test method ofclaim 1 further comprising changing a component of an emissions controlsystem of the first or second vehicle after the controlling, and againcontrolling the accelerator pedal, accelerator pedal signal, fuelinjector, manifold pressure, motor controller, or throttle valveaccording to the speed schedule such that the dynamometer, or theanother dynamometer, programmed with the road grade information andoperatively arranged with the first or second vehicle applies a load tothe first or second vehicle that reflects the road grade information. 7.The test method of claim 1 further comprising deriving wind loadinformation from the test schedule torque outputs, and furthercontrolling the accelerator pedal, accelerator pedal signal, fuelinjector, manifold pressure, motor controller, or throttle valveaccording to the speed schedule such that the dynamometer, or theanother dynamometer, programmed with the wind load information furtherapplies a load to the first or second vehicle that reflects the windload information.
 8. A test method comprising: deriving wind loadinformation from test schedule torque outputs generated by a dynamometeroperatively arranged with a first vehicle; and controlling anaccelerator pedal, an accelerator pedal signal, a fuel injector, amanifold pressure, a motor controller, or a throttle valve associatedwith the first or a second vehicle according to a speed schedule suchthat the dynamometer, or another dynamometer, programmed with the windload information and operatively arranged with the first or secondvehicle applies a load to the first or second vehicle that reflects thewind load information.
 9. The test method of claim 8 further comprisingmeasuring emissions of the first or second vehicle during thecontrolling.
 10. The test method of claim 8 further comprising changinga calibration of the first or second vehicle after the controlling, andagain controlling the accelerator pedal, accelerator pedal signal, fuelinjector, manifold pressure, motor controller, or throttle valveaccording to the speed schedule such that the dynamometer, or theanother dynamometer, programmed with the wind load information andoperatively arranged with the first or second vehicle applies a load tothe first or second vehicle that reflects the wind load information. 11.The test method of claim 10 further comprising measuring emissions ofthe first or second vehicle during the again controlling.
 12. The testmethod of claim 8 further comprising changing ambient conditions of thefirst or second vehicle after the controlling, and again controlling theaccelerator pedal, accelerator pedal signal, fuel injector, manifoldpressure, motor controller, or throttle valve according to the speedschedule such that the dynamometer, or the another dynamometer,programmed with the wind load information and operatively arranged withthe first or second vehicle applies a load to the first or secondvehicle that reflects the wind load information.
 13. The test method ofclaim 8 further comprising changing a component of an emissions controlsystem of the first or second vehicle after the controlling, and againcontrolling the accelerator pedal, accelerator pedal signal, fuelinjector, manifold pressure, motor controller, or throttle valveaccording to the speed schedule such that the dynamometer, or theanother dynamometer, programmed with the wind load information andoperatively arranged with the first or second vehicle applies a load tothe first or second vehicle that reflects the wind load information. 14.A test method comprising: deriving dynamometer road load controlparameters for a first vehicle from test schedule torque outputsgenerated by a dynamometer operatively arranged with the first vehicleor with a second vehicle; and controlling an accelerator pedal, anaccelerator pedal signal, a fuel injector, a manifold pressure, a motorcontroller, or a throttle valve associated with the first or a secondvehicle according to a speed schedule such that the dynamometer, oranother dynamometer, programmed with the dynamometer road load controlparameters and operatively arranged with the first or second vehicleapplies a load to the first or second vehicle that reflects thedynamometer road load control parameters.
 15. The test method of claim14 further comprising measuring emissions of the first or second vehicleduring the controlling.
 16. The test method of claim 14 furthercomprising changing a calibration of the first or second vehicle afterthe controlling, and again controlling the accelerator pedal,accelerator pedal signal, fuel injector, manifold pressure, motorcontroller, or throttle valve according to the speed schedule such thatthe dynamometer, or the another dynamometer, programmed with thedynamometer road load control parameters and operatively arranged withthe first or second vehicle applies a load to the first or secondvehicle that reflects the dynamometer road load control parameters. 17.The test method of claim 16 further comprising measuring emissions ofthe first or second vehicle during the again controlling.
 18. The testmethod of claim 14 further comprising changing ambient conditions of thefirst or second vehicle after the controlling, and again controlling theaccelerator pedal, accelerator pedal signal, fuel injector, manifoldpressure, motor controller, or throttle valve according to the speedschedule such that the dynamometer, or the another dynamometer,programmed with the dynamometer road load control parameters andoperatively arranged with the first or second vehicle applies a load tothe first or second vehicle that reflects the dynamometer road loadcontrol parameters.
 19. The test method of claim 14 further comprisingchanging a component of an emissions control system of the first orsecond vehicle after the controlling, and again controlling theaccelerator pedal, accelerator pedal signal, fuel injector, manifoldpressure, motor controller, or throttle valve according to the speedschedule such that the dynamometer, or the another dynamometer,programmed with the dynamometer road load control parameters andoperatively arranged with the first or second vehicle applies a load tothe first or second vehicle that reflects the dynamometer road loadcontrol parameters.
 20. The test method of claim 14 further comprisingderiving wind load information from the test schedule torque outputs,and further controlling the accelerator pedal, accelerator pedal signal,fuel injector, manifold pressure, motor controller, or throttle valveaccording to the speed schedule such that the dynamometer, or theanother dynamometer, programmed with the wind load information furtherapplies a load to the first or second vehicle that reflects the windload information.